Fluids based on fluorocarbon compounds are widely used in numerous industrial devices, in particular air-conditioning, heat pump or refrigeration devices. A common feature of these devices is that they are based on a thermodynamic cycle comprising the vaporization of the fluid at low pressure (in which the fluid absorbs heat); the compression of the vaporized fluid to a high pressure; the condensation of the vaporized fluid to liquid at high pressure (in which the fluid loses heat); and the expansion of the fluid to complete the cycle.
The choice of a heat transfer fluid (which can be a pure compound or a mixture of compounds) is dictated on the one hand by the thermodynamic properties of the fluid, and on the other hand by additional constraints.
In particular, depending on the flammability of the fluid, more or less restrictive safety measures have to be taken when using this fluid in certain applications, or the use of this fluid may even be prohibited in other applications.
Another important criterion is that of the impact of the fluid considered on the environment. Chlorinated compounds (chlorofluorocarbons and hydrochlorofluorocarbons) therefore have the disadvantage of damaging the ozone layer. Non-chlorinated compounds such as hydrofluorocarbons, fluoroethers and more recently fluoroolefins (or fluoroalkenes) are therefore now generally preferred to them. Moreover, fluoroolefins generally have a short lifetime, and therefore a lower global warming potential (GWP) than the other compounds.
In this respect, documents WO 2004/037913 and WO 2005/105947 teach the use of compositions comprising at least one fluoroalkene having three or four carbon atoms, in particular pentafluoropropene and tetrafluoropropene, as heat transfer fluids.
Documents WO 2007/053697 and WO 2007/126414 disclose mixtures of fluoroolefins and other heat transfer compounds as heat transfer fluids.
However, olefin compounds have a tendency to be more flammable than saturated compounds.
There is therefore a real need to obtain and use heat transfer fluids less flammable than those of the state of the art without degrading the GWP of the heat transfer fluids.
Moreover, there is a need to obtain and use heat transfer fluids having a GWP lower than that of the heat transfer fluids of the state of the art, without increasing the flammability of the heat transfer fluids.